The Mars Curiosity Rover is powered by plutonium, which is a nuclear power source to charge its batteries and fuel its onboard systems throughout its planned two-year mission on Mars. The battery packs are made up of two separate battery systems, charged by the nuclear power source. These battery packs are 2 Lithium-Ion rechargeable batteries to meet peak demands of rover activities when the demand temporarily exceeds the generator's steady electrical output levels. The Power Source unit produces enough electricity to power all Mars rover activities.

If you look at the tail section of the Curiosity Mars rover, you will notice a cylindrical unit sticking up at a 45 degree angle. This unit is the Power Source that runs everything on Curiosity. Below are detailed technical specifications off of the JPL NASA Web site.

Reliability: NASA has used this power source reliably for decades, including the Apollo missions to the moon, the Viking missions to Mars, and the Pioneer, Voyager, Ulysses, Galileo, Cassini, and New Horizons missions.

Safety: Built with several layers of protective material to contain its fuel in a wide range of potential launch accidents, verified through impact testing. Manufactured in a ceramic form, is not a significant health hazard unless broken into very fine pieces or vaporized and then inhaled or swallowed. In the unlikely event of a launch accident, those who might be exposed would receive an average does of 5 to 10 millirem. The average American receives 360 millirem of radiation each year from natural sources, such as radon and cosmic rays.

The Mars Rover Curiosity is projected to last two years off of its nuclear power source and battery pack combination. Curiosity’s power source could last as long as six to twelve years. This would keep the operation running longer, as seen in previous Mars rovers, such as Spirit and Opportunity. For more information on the Curiosity Mars rover, check out the following sources.